Kevlar on the keel

[waynemunro]

For better or worse my boat (weekender) has a plywood keel. I have resolved to put down a layer or two of kevlar, and a few layers of glass cloth.

Does anyone have any opinion on how far down the keel I should lay the kevlar ? I was thinking just going down about 40mm (1 3/4 inches ?). I can get the cloth in 1.2m widths only, and I can't afford to buy a long enough length to do the job (it is NZ$67/m (bout US$35)), so I am going to have to put pieces together along the length, I figure I can either overlap them, or put down two layers with alternating joins, not sure what is the best way to go here, not sure if the overlaps will show through due to the extra thickness if there is not two layers all along.

the cloth is 9oz , or there is a slightly cheaper 5oz cloth (at NZ$45/m).

anyone got any opinions on if my plan is fundamentaly flawed ?

NB. interestingly the guy I was talking to me on the phone specifically told me that you cannot sand kevlar - as has already been quite graphically shown here

[TexasPhil]

Wayne,

You opened a big can of worms... this is one of the endless debate topics...

Lots of people say covering the keel is good, others say it leads to rot, etc.

So, hang on tight, the ride is about to get bumpy!

My vote is on using the stuff... Just make sure it is dried out well before hand. I live in an area where most of the lakes are built with rock and stone... so I need some extra protection. I got some thick glass from RAKA that is just a foot wide, or so. I think it will work out well.

Just make sure to apply your layers from back to front, so the water does not try to delaminate your layers.

Phil

[Barry Pyeatt]

Wayne,

I can give you a web address for a Kevlar tape supplier. It is quite affordable and they ship all over the world.

[waynemunro]

thanks for the thought on the direction of laying the laminations phil.. I had not thought of that.. though the glass I am putting over the kevlar will hopefully assist in stopping the water from delmainating.. good to take what precautions can be taken.

That address would be good to have a look at Barry (maybe PM me with it? ), to see if the prices are a lot cheaper, and if they ship in reasonable times.. I have to admit that I don't really want to hold up to project too long to try and get tape rather than using the 1.2m cloth. The place that I can get the cloth from is about 10 blocks away and I can just call in on the way home from work one day to get it

Hoping to get through to the glassing stage this weekend, though that might be a bit of a pipe-dream.

[Bob Taylor]

I used a Kevlar strip from RAKA Marine over two layers of 6 oz glass. Forget sanding it, but a right angle grinder with a 40 grit disc will eat it up really quick. WELL WORTH THE EXPENSE AND EFFORT!!!

[richard]

I am also making my keel in plywood - 3 layers of 22 mm.

I intend to put a hardwood strip on it when finished

Any comment?

Richard

[Barry Pyeatt]

Richard,

I think that is a good decision. You can lay one or more layers of relatively thin hardwood epoxied together from the tip to the rear edge of the transom and it will give you a much better surface along the bottom edge. The thin layers will conform to the shape of the keel. They don't have to be in long lengths either. They can overlap. The plywood edge is the most fragile part of the panel. The protection these strips will provide may prevent a lot of frustration later on.

I would lay them up and simply tape them down to hold them inplace while they setup. An occasional screw thru them will pull them down tight. After they setup the screws can be removed and the holes filled with epoxy.

Once you have it built up to the thickness you are after the edges can be rounded over with a router.

[Florin {VACATIONER}]

The best place for kevlar is in the bullet proof vests and the hell away from garage. That little experiment was not a good thing for us. You can't sand that stuff, so unless you keep putting resin on it to build it up and paint it, forget it. It was one of the biggest pains in the a$$ we've had with this boat (other than the gelcoat incident). As soon as I started sanding it the damned thing started fuzzing. You just can't get rid of the yellow fuzz no matter what you do. Then we sanded it off the keel. We've had a 6" strip all along the keel like a cap. It took a good 2 hrs to sand it off with the belt sander and 30 grit and because it was really awkward to sand I've had a back ache for 3 days. I almost burned out the motor on the sander. I also filled half of a trash bag with yellow fuzz. Everything was fuzzy in the garage, and it got everywhere including my shorts. I guess I've had a bad case of the yellow fuzzitis.

My advice would be to stay away from it and just paint the keel, don't put on anything, but that's a personal preference; we used to have two layers of glass under the kevlar as well. Well, that got chewed up by the sander as well, so now there's just paint there which suits me just fine ... some guys actually got the stuff on and are happy with it. I'm happy without it.

Good luck.

[waynemunro]

that is going to be one meaty looking keel that you are going to produce with three 22mm ply layers Richard. I used 18mm (to give the same thickness as the design wooden one), and people coming to look at my boat to be still comment on how thick and strong the keel/stem looks

Well one thing seems clear about this discussion.. there is no way to sand kevlar A guy here at work had a company making replica cars a few years back, and he had a story very similar to your florin.. walked away with lots of yellow fuzz and a bitter taste in his mouth. I intend putting glass over the top of the kevlar, so that should take care of that problem hopefully - the guy in the shop thought that was a fine plan.

I don't know if I will do the hardwood strip plan, I can see that it looks like a good idea, but I think lazyness and impatience are too powerful a force in my life

[Guest mncalder]

Wayne,

Count me as a satisfied kevlar user. Unlike the other posters I used what Raka sells as 'Kevlar Felt'. This stuff is about 1/4" thick and will suck up a lot of epoxy. But it is like having a strip of iron molded to the keel bottom. When the rest of my boat is rotting away at the bottom of the Atlantic, the keel will still be there, bound by this indestructable vice. As for how much, I ran it along the full length of the keel up to roughly the waterline of the stem, and about 1"-2" over the edge. Yes, it forms an unsightly bulge that all the scuba divers find aesthetically unappealing.

Matt

[ken connors]

Barry, ive always leaned toward your theory that a keel not glassed is more easily (and more likely) maintained. how do you feel about using the kevlar felt previously mentioned with the rest of the keel just epoxied and painted.

[Guest Anonymous]

I don't understand why some of you are having problems with the Kevlar.

I 've used the Kevlar tape many times and it just lays flat and sets up nice and smooth. If you are using Kevlar felt that is a different breed of material.

[Barry Pyeatt]

Ken,

I've been against covering the keel with glass for a number of reasons. Primarily because it takes quite a bit of abuse and glass tends to hide that.

Secondly because builders use all manor of materials to build the keel and wood moves. Those that use plain sawn lumber or riff cut lumber will have the wood cup on them and separate one lamination from the other. Small voids will open up between the laminations and moisture will collect there. This will be more prevalent with builders in areas with temp extremes from below freezing to mid 70's and above. Those that read the reports from some of them that have experienced that will know that happens.

These boats are stored outside over the off season and largely ignored until Spring. When the tarps come off and they get ready to go sailing again all sorts of problems present themselves. Even with the best of epoxy coatings and glass and epoxy the wood will still expand and contract when subjected to temp and humidity extremes. Some of the problems are going to be concealed by the glass. I would rather have them be apparent and allow me to address them before they get so bad that they become major repairs.

I have several thoughts about these keels when it comes to protecting them. Depending upon the wood used to build it, I would add a strip that could be replaced as we have discussed. I would also do it in sections so that sections could be replaced instead of the entire strip. White Oak, Ash, Hickory...or other hard woods that can take abuse. Build them up in thinner layers so that they conform to the curves of the stem and keel. Epoxy the layers together so they retain the curve. My personal recomendation would be to soak them in hot linseed oil and then let them dry as much as possible and install them over a finished keel.

It is going to get beat up so why not let the sacrificial strip take the abuse instead of the keel itself?

I am a believer in Kevlar tape for keel protection as well, particularly on the front of the stem and the bottom third, with two or three layers on the stem and bulb of the keel for boats being used in areas with rocky bottoms and rocky beaches.

I know that image of Mike Stevenson bringing the Weekender into the dock seems to a novice like a hard knock, but most everyone will duplicate it or impact even harder than that before they get used to their boats. Softer wood keels will have damage done to them, again, would you rather not see the damage by covering it with glass? I don't personally. The kevlar tape conforms well to the shape of the keel and shouldn't require any significant sanding and certainly not grinding. The idea is for the tape to do its job protecting the area from impacts. No it isn't as nice looking as a production glass hull or gelcoat.

I also feel that if you are using felt or mat glass or kevlar, you are simply using the wrong product for this area. They have their places, and it is generally in glass layup in molds. I think we can have wonderfully protected hulls with two layers of glass and not using the mat. Many of those products have uses in production glass boats or surfboards, etc. At least in my experience they are not commonly used on wood boats.

Some of the builders seem to want their boats to look as if they came out of a mold and strive for that ultra high gloss, smooth gelcoat finish. My personal opinion is that they can work to achieve any level of finish they want. I don't hold any of that against them in any way. I've built to that level when the desire or need is there. But it isn't a piece of furniture or a classic yacht.

I think a painted keel will hold up just fine, it will get scratched, and dinged and it can be sanded and repainted and touched up. I'm personally into a finish that can be termed a 10' finish. It looks just fine from 10' away. I want to enjoy the boat, not worry about scratching it.

I would rather replace a sacrificial strip than worry about how to repair a beautifully finished glass job. I also think that thinned epoxy saturation of the open end grain is worth it prior to finishing.

I'm particularly interested in seeing how the laminated plywood keels will hold up. Primarily because there is less potential for voids occuring and the wood is much more stable so glass encapsulation might be more practical. Then apply a sacrificial strip or kevlar tape and enjoy the boat.

Sorry, got a little carried away. :oops:

[Frank Hagan]

I'm usually an advocate of not glassing the keel, but this is different: these are PLYWOOD keels.

Plywood is super-susceptible to water infiltration, even marine plywood, along the end grain edges. That's the entire bottom of the keel. The water will wick into the wood FAST. A laminated 1 x 12 keel, on the other hand, presents to the bottom the side grain of the board rather than the end grain. Well glued and sealed, it doesn't need glass. But plywood ... I think you have to use epoxy to seal all the edges first ... really letting it soak in. Then a layer of either kevlar, glass or a sacrificial hardwood, and again ... plenty of epoxy.

It may be a great alternative construction for the keel, but I think plywood will have to be treated differently than solid wood.

[Barry Pyeatt]

AMEN! The plywood keels will also check with weather changes. So the glass will help with that. But I would also recommend that the edges be super saturated with thinned epoxy before finishing. Then protect them.

This is a whole new area that may offer some real potential for those builders that have trouble locating good 1X12 stock.

[TexasPhil]

Barry,

I think you are even longer winded than I.

I am not clear about a couple of things that you suggest, that I am interested in doing.

I live in the area of rocky bottoms and beaches... so I want more protection. I have the standard tripple 1x12 keel and marine ply hull.

I am interested in your suggestion of sacrificial hardwood strips, and the kevlar tape (would glass tape work... I have some of it?).

I could see steaming the strips and applying, but not sure what you mean about the linseed oil. What would be the advantage over steam? How do you do it? Then, how to you attach to the keel? And what parts to you apply the kevlar or glass tape?

Thanks,

Phil

[Barry Pyeatt]

Phil,

Yes, I do get carried away once in a while. :?

I suggested thinner strips epoxied together for a couple of reasons:

First is because it is difficult to bend a strip of hardwood to the curves of the stem and down to the keel without steaming. The thinner strips can follow the curves with only minimal hassle.

Second is that once you lay them up and epoxy them together, they retain the curves and don't want to spring off.

The linseed oil is for protection from moisture. Instead of using varnish or paint, the linseed oil is a traditional protection for wood exposed to the weather. Soak the wood in hot linseed oil and let it absorb as much as possible. Then wipe it off and let it sit for about a week to dry. Then re-attach it to the keel. It gets banged on and roughed up and the linseed oil still protects it. It is also easy to wipe an additional coat on it now and then. Once it has dried, it can be painted with an oil based paint. Latex doesn't work all that well over it.

Regarding the fiberglass for protection: It doesn't offer much in the way of abrasion or impact resistance. It will give you a better surface for finishing and provide some waterproofing as long as it is intact. But once it is fractured, it allows water to enter and the cracks can be so fine as to not attract attention. Several layers of heavier cloth will help provide more to wear on but it is still low impact resistance.

For a link to Kevlar Tape:

http://www.fiberglasssupply.com/Product_Catalog/Reinforcements/reinforcements.html

Scroll down to Kevlar Tapes. I would use the 3" tape. One layer the full length of the keel from the bow eye for trailering to the stern. An additional layer from the midpoint on the stem to about a third of the way back on the keel. If you are using the strip of hardwood, then only one layer of Kevlar is necessary to provide good protection. Two on the stem and paint over it.

[waynemunro]

I would like to thanks everyone for their comments and the many good ideas, it has helped me decide what to do with my keel - I am going to run out today to get some epoxy thinners and will give those ends a good soaking, seems a simple thing to do which may save much trouble in the future.

[Robert Cox]

Wayne and Phil, here is a picture of my solution to the beaching and keel wear problem. Living in Florida there a lot of sand beachs and rock beachs as well. Both are hard on your keel. I will do most of my sailing around the keys where there is a lot of sholow water. I didn't want to worry about what I was doing to the bottom of my keel when I beached at that out of the way sandy cove for lunch.

Bob

[waynemunro]

that looks like a nice feature robert, thanks for the picture. How have you attached it ?

the channel on your trailer looks good too - just shopping sround to see what is going by way of trailers at the moment.